Energy Flow “The Carbon Cycle”

Where do we get all of our energy?  Directly or indirectly, almost all organisms get the energy needed for metabolism from the sun.  Photoautotrophs use the sun’s rays to make organic compounds  These compounds store energy and serve as food for heterotrophs)  What are chemoautotrophs?

The Path

Building Molecules  Photosynthesis – light energy is used to build glucose – C 6 H 12 O 6  Chemosynthesis – chemical energy is used to build organic molecules.

Breaking Down Molecules  Heterotrophs break down glucose to gain energy to carry out life activities.  They break down the glucose to make ATP (Adenosine Triphosphate)

PHOTOSYNTHESIS Diagram of Process Diagram of Process Diagram of Process Equation 12 H 2 O + 6 CO 2 + Light energy  C 6 H 12 O O H 2 O

Light is the main ingredient  White light is a combination of all colors of the visible light spectrum.  Observe the visible light spectrum using a spectrophotometer.  Visible light ranges from wavelengths measuring ~400 nm (violet) to ~700 nm (red) on the electromagnetic spectrum.

 How do we see color?  Pigments absorb certain wavelengths of light and reflect all others.  Look at the red heart – What’s going on with the pigments?

Plant Pigments  Chlorophyll a  Chlorophyll b  Carotene  Xanthophyll  Dark Green  Yellow-green  Orange  Yellow

Light Phase  Stage 1 – Energy is captured from sunlight.  Photosystem 2 (PS2) – Step 1  Photolysis – Light hits the thylakoid membrane of a plant and the electrons go through the electron transport chain to produce a lot of energy (ATP) to split water molecules  12 H 2 O  24 H O 2 + Energy  H+ trapped by NADP + forming NADPH to carry the energy used during the dark phase (when glucose is made).

 Photosystem 1 (PS 1) – Step 2  Phosphorylation – THE RECHARGEABLE BATTERY!  When ATP loses a phosphate, energy is released and ADP is formed.  You gain phosphates by breaking down the food you eat.  ATP is the energy needed to fuel the dark reaction.

Dark Phase  Stage 2 – The chemical energy stored in ATP and NADPH powers the formation of Glucose, using CO 2.  To fix carbon (change it into a useable form), you use CO 2 and combine it, split it and basically put it through the wringer (the Calvin Cycle) and then combine it with ATP and NADPH to form C 6 H 12 O 2 and give off H 2 O.

The Process In General Light Hits Thylakoid Light Phase Excites Electrons (move thru ETC) H 2 O Splits (due to enzyme) O2O2 ATP NADPH Dark Phase CO 2 Glucose Calvin Cycle ATP  ADP NADPH  NADP +

RESPIRATION Equation C 6 H 12 O O H 2 O  12 H 2 O + 6 CO 2 + Energy

Step One - Glycolysis C 6 H 12 O 6 is broken down into two 3-carbon molecules called pyruvate (aka – pyruvic acid) C 6 H 12 O 6 is broken down into two 3-carbon molecules called pyruvate (aka – pyruvic acid) 4 ATPs generated but 2 ATPs required so the net ATP production is??? 4 ATPs generated but 2 ATPs required so the net ATP production is??? 2

If O 2 is Present… Then it’s AEROBIC RESPIRATION 1. Pyruvate enters mitochondrion 2. Pyruvate  2-carbon molecule (acetyl) CO 2 is released here. 3. Acetyl attaches to coenzyme A to form acetyl-CoA

Acetyl-CoA enters the Krebs Cycle… Acetyl-CoA enters the Krebs Cycle… C C CO 2 NADH FADH These are electron carrying molecules which will dump electrons into ETC CCCCCC CCCCC CO 2 CCCC 2 ATPs CCCC Acetyl-CoA joins 4-carbon molecule

ELECTRON TRANSPORT CHAIN Occurs in the inner membranes of the mitochondria. Occurs in the inner membranes of the mitochondria. NADH and FADH donate electrons NADH and FADH donate electrons Electrons pump hydrogen ions across membrane Electrons pump hydrogen ions across membrane Phosphate added to ADP to form ATP Phosphate added to ADP to form ATP

If O 2 is NOT Present… Then it’s ANAEROBIC RESPIRATION… Then it’s ANAEROBIC RESPIRATION… Another name for this is fermentation. Another name for this is fermentation. There are two types of fermentation There are two types of fermentation LACTIC ACID LACTIC ACID ALCOHOLIC ALCOHOLIC

LACTIC ACID FERMENTATION Pyruvate Glucose Lactic Acid During vigorous exercise, lactate builds up In muscles when the tissue is deprived of oxygen. This allows glycolysis to still produce ATP as long as there is glucose but only 2 ATPs per molecule of glucose – MUCH LESS EFFICIENT THAN AEROBIC RESPIRATION.

ALCOHOLIC FERMENTATION Pyruvate Glucose Ethyl Alcohol This happens in certain bacteria and fungus. For centuries this has occurred during the production of various alcoholic beverages such as beer and wine. This allows glycolysis to still produce ATP as long as there is glucose but only 2 ATPs per molecule of glucose – MUCH LESS EFFICIENT THAN AEROBIC RESPIRATION. CO 2

The Process In General GlycolysisGlucose (Net) 2 ATP No O 2 O2O2 Krebs Cycle 2 ATP ETC 34 ATP Fermentation Lactic Acid Ethanol